When we think of farm animals, we likely don’t think of carp. But this family of freshwater fish — which includes the three most populous farmed fish species in the world: crucian carp, silver carp, and catla — is likely the most numerous farmed vertebrate animal in the world, with an estimated 25-95 billion farmed every year. (About 62 billion chickens are farmed every year, but each is farmed for just 5-8 weeks, whereas carp are farmed for 12-14 months, meaning far more carp are alive at any time.)

Fish are the forgotten farm animal. Of the more than 100 undercover investigations that US animal advocates have done to expose abuse of farm animals, just one focused on fish. For a long time scientists questioned if fish could feel pain, though our ongoing internal investigation suggests there’s about as much evidence that some fish can feel pain as there is for birds (for more on that debate, I recommend these 37 scientific commentaries).

When we do think of fish, it’s likely of wild ones. But the wild fishing industry hasn’t grown since 1988, largely due to the depletion of wild fisheries. By contrast, fish farming has grown sevenfold over the same time period, and now accounts for the majority of fish consumed by humans globally, including in the US. (More wild fish are still slaughtered for non-human consumption: about a third of captured wild fish are fed to farm animals, including farmed fish.)

So what can we do to help farmed fish? First, we need better research and data on a few topics:

• Farmed fish numbers. The Food and Agriculture Organization, which tallies land farm animal numbers, doesn’t count fish — it only reports tons produced. The best numbers I know of come from Alison Mood’s extrapolations from FAO data, which, adjusted for growth since 2010, suggest there are 50 to 170 billion fish farmed annually worldwide.
• Fish welfare. Concern for fish welfare is not new: the ancient Roman treatise On Agriculture advised farmers to provide their fish with enriched environments “so that, though they are prisoners, the fish may feel their captivity as little as possible.” But aside from a few papers (e.g. here and here), modern animal welfare science has yet to answer basic questions like what kinds of environments fish prefer to live in.
• Species differences. Almost all farmed pigs are derived from one species, sus scrofa, and confined in similar conditions globally. But humans farm finfish from 362 different species — plus another 62 species of crustaceans, 104 of molluscs, six of frogs and reptiles, and nine of aquatic invertebrates (all beyond the scope of this newsletter). These differences make providing for fish welfare harder: while territorial species like rainbow trout get stressed by overcrowding, shoal-based species like Arctic charr get stressed by under-crowding.

Second, we need to focus on the regions, systems, and practices where the most fish are at stake:

• East Asia. Controversy around fish farming has centered on the US industry, which is small and hasn’t grown in two decades. But 88% of fish are farmed in Asia, mainly for domestic demand — the average East Asian eats three times more fish than the average American.
• Dense inland systems. The few fish welfare initiatives to date have focused on sea cage farming in Norway and Scotland, where the industry is more receptive. But fully 87% of fish are farmed inland, typically in tanks or ponds. When I visited inland fish farms in India in March, the ponds didn’t appear obviously overcrowded. But mortality rates above 50% in common carp farms suggest that many fish are in poor health, and likely poor welfare.
• Slaughter. I witnessed “harvest” at one large Indian carp farm: fish took minutes or hours to die, as they suffocated or were crushed to death. Those fish that survived may have suffered a worse fate — we saw fish live disemboweled at the market hours later. Given that 46% of fish globally are sold “live, fresh or chilled,” it seems unlikely the fate of these fish was unique.

Third, we should consider how we can leverage existing schemes, trends, and policies to help fish:

• Adding animal welfare to fish sustainability certifications. About one in 20 fish farms worldwide is sustainability certified. Two schemes predominate: the Aquaculture Stewardship Council and Best Aquaculture Practices each now have over 1,000 certified facilities, and all fish sold at Kroger and Walmart carry the latter certification. But the few words their standards contain on animal welfare are vague and voluntary.
• Reducing fish waste. With governments from China to the US encouraging citizens to eat more fish, reducing consumption will be tough. But roughly half of US seafood and a third of seafood elsewhere is never consumed — it’s lost to waste. Conservationists have rightly focused on reducing bycatch, but bycatch accounts for barely a third of fish wasted in the US. Advocates could support institutional food waste reduction work. (New feeds might also reduce the number of wild fish caught to feed farmed fish. But sources of these fish are already supply-constrained — volume hasn’t increased since 2000 despite booming demand — so alternative feeds might just remove a constraint to the further expansion of fish farming.)
• Adding fish to animal welfare policies. The FAO notes that "Supermarket chains and large retailers are increasingly the key players in setting product requirements.” For US chains these standards currently exclude fish welfare. But advocates can look for inspiration to the UK, where major chains, including Waitrose and Tesco, are proactively addressing fish welfare. Advocates could also build on the animal welfare codes of the World Organization for Animal Health, Council of Europe, and European Union, which, though all weak and unenforceable, are revolutionary in affording some protections to fish.

Next month I’ll examine the importance of three commonly cited structural supports for the factory farming system: antibiotics, farm subsidies, and lax antitrust enforcement.